An obscure illness, disease or condition affecting a comparatively small number of people, but with symptoms somewhat similar to one or more different and more common illnesses.

It is named because these diseases/conditions are sometimes misdiagnosed by well meaning (but often inexperienced) doctors when something far more common is actually the cause. Medical students are told "remember, if you hear hoof beats, think horses, not zebras".
Doctor 1 - "I think this patient may have Castleman's disease"
Doctor 2 - "Castleman's disease is a zebra, there are far more likely causes of his fever and weight loss."
by PiemasterUK December 8, 2010
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TWENTY-FIVE sizes larger than a A bra.
Fat beatch had milkers so large that she needed a zebra to contain them.
by Cosmicstargoat April 27, 2004
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(n) common slang term for referees or field officials in certain sports (particularly in American football) due to the white and black striped uniforms
That zebra should be hunted down for that assinine 'pass interference' call.
by methodmadness March 18, 2004
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Like a horse, but better. Zebras have many stripes, and a sophisticated color palette making them superior to every other creature in the animal kingdom. They are practically the real-life version of a unicorn, only with less sparkles and more stripes. Zebras are so self confident, they don’t try to blend in, they stand out. Zebras are very rare, and spotting one is a once in a lifetime experience. If you find a zebra in the wild, make sure you catch it and bring it home with you for good luck.
“Omg, look over there! Is that a zebra?”

“That’s so cool, I’ve heard they can grant wishes!”

“Yeah, dude. They’re like the real life version of unicorns.”
by monkeytoes January 18, 2021
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Any of several swift, wild, horselike African mammals of the genus Equus, having distinctive overall markings of alternating white and black or brown stripes.
Is that Zebra black with white stipes or white with black stripes?
by Caitlinn July 7, 2005
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